342 
MESSRS. J. B. LAWES AND J. H. GILBERT ON THE RESULTS OF 
It lias before been shown, that a given amount of nitrogen applied as nitrate of soda 
gave more produce than the same amount applied as ammonia-salts, whether these 
nitrogenous manures were respectively used alone, or in conjunction with a mixed 
mineral manure supplying in excess all the mineral constituents of the crop, except 
silica. It was also shown that, when used alone—that is to say, when the whole of the 
mineral constituents (except soda) had to be obtained from the soil itself—275 lbs. of 
the nitrate yielded nearly as much produce, containing more of some, and nearly as 
much of all, of the mineral constituents, as when 550 lbs. were employed. 
It is now seen that, when used in each case in conjunction with the mixed mineral 
manure, the smaller amount of nitrate does not give nearly so large an actual amount 
of produce as the larger; but the smaller amount does give a greater produce of hay, 
and a greater yield of nitrogen in the crop, for a given amount of nitrate used. Thus, 
with the mineral manure and the larger amount of nitrate there was, over the 
18 years, an average per acre per annum, of about 57 cwts. of hay, containing a little 
over 69 lbs. of nitrogen; and with the smaller amount of nitrate there was an average 
of 46^ cwts. of hay, containing about 62§- lbs. of nitrogen. This larger yield for a 
given amount of nitrate used, was associated with, and doubtless greatly dependent on, 
the much greater complexity of herbage than when the more forcing excessive amount 
was employed. The herbage of plot 16, with the mineral manure and the smaller 
amount of nitrate, was, indeed, more complex than that of any other plot yielding the 
same weight of hay ; its gramineous herbage was in a less degree made up of a few very 
freely-growing grasses ; it contained a considerable and an increasing amount of legu¬ 
minous herbage—much more than in the other cases with an equal amount of crop ; 
and finally, it contained a large number, and a considerable percentage by weight, of 
miscellaneous species. Although the herbage of some of the best pastures of some of 
the best grazing districts of the country comprises but a small total number of species, 
it nevertheless includes a considerable proportion of other than gramineous species, and 
it is especially rich in Leguminosse. Comparing the produce of the different experi¬ 
mental plots, however, as a rule, the more complex the herbage, the higher is the 
quality of the hay, and it is especially so when leguminous species are in fair propor¬ 
tion ; and, doubtless, the quality of the hay of plot 16 would be higher than that of any 
other of the plots yielding an equal weight of produce. The result is, then, that with 
the mixed mineral manure and a not excessive amount of nitrate of, soda, we have 
both a large actual amount of produce, a large amount in proportion to the nitrate 
used, and a comparatively high quality of the hay. 
12. 400 lbs. Ammonia-Salts, and Superphosphate of Lime; Plot 4-2. 
In the experiments hitherto considered in which nitrogenous and mineral manures 
have been used together, the mineral manures have consisted of a complex mixture, in 
some cases supplying an excess of all the mineral constituents of the crop except silica, 
